Breast cancer related lymphedema (BCRL), characterized by arm swelling, impaired function and bothersome symptoms, is a common, persistent, often progressive adverse event of breast cancer diagnosis and therapy, exacerbated by obesity and sedentary lifestyle. The WISER Survivor Trial (Project 2) will assess in a multi-ethnic cohort of ovenweight and obese post-menopausal women witht BCRL the incremental clinicai effectiveness (lymphedema flares, cellulitis, quality of life) of exercise only, weight loss only, and exercise and weight-loss combined compared with a usual care control group. While BCRL incurs substantial health care costs (significant portions of which are borne by patients), reduces productivity and reduces quality of life, empirical data are sparse. Effective behavioral interventions such as exercise training and weight loss that temporize BCRL, mitigate its impact and prevent progression often are not reimbursed; third party payers rarely cover supplies required to mitigate BCRL. As a consequence, the current insurance structure perversely places breast cancer survivors at needless risk of BCRL adverse events and sequellae and may increase costs as a result of increased downstream complications (e.g., outpatient care and hospitalizations for repeated episodic lymphangitis and cellulitis; physical therapy for BRCL flares and symptomatic exacerbations). Thus, there is a compelling need to better characterize the medical economic impact of BCRL, as well as its short- and long-term health consequences. Project 3 will; (1) assess BCRL direct medical care costs; (2) assess the incremental cost-effectiveness of the Project 2 WISER Survivor interventions; and (3) model the impact ofthe WISER Survivor interventions over an extended time frame. The novel methodological approaches developed to define and identify BCRL cases combining and integrating data from patient reports, administrative claims and national language queries of electronic medical records will inform criteria to identify and select BCRL patients for future studies, as well as establish the validity of alternative methods, while demonstrating the feasibility and potential value of this approach for other medical conditions.